Effect of cadmium on production of superoxide radical and activities of catalase and superoxide dismutase (SOD) in homogenates, cytosolic and mitochondria) fractions of liver, kidney and testis of rats was studied. Inhibition dose (Iso), concentration of cadmium required for inhibition of the enzyme activity to 507o level, was calculated by probit method.
Cadmium "enhanced the production of superoxide radical in homogenate as much as 10.6, 1.3 and 2.8 times than control value in liver, kidney and testis, respectively, when cadmium concentrations ranged from 0.45 to 0.50-mM.
Activity of catalase in homogenates was inhibited by addition of cadmium ranging from 0.1 to
Y + 50.0 MM. The I5o of cadmium for catalase in homogenates of liver, kidney and testis were 18, 86, 34.59 and 0.79 mM, respecively. Cadmium also inhibited the activities of Cu,Zn=SOD in.cytosol fractions and Mn-SOD in mitochondria) fractions. The Iso for Cu,Zn-SOD activity in cytosol fractions of fiver, kidney and. testis were 0.049, 0.118 and 0.030 m´ M, respectively, and for Mn-SOLD activity in mitochondrial fractions were 0.905, 0.713 and´0.510 mM, respectively.
In vitro inhibition of the enzyme activities by cadmium was dose-dependent. The inhibitory effect of cadmium on enzyme activities was most potent in testis suggesting that testis would be one of the most sensitive organs to cadmium.
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